Type 1 diabetes (T1D) results from autoimmune destruction of insulin-producing pancreatic ?- cells - a long asymptomatic period spanning many months to years. Currently, autoantibodies to islet cell antigens serve to identify those at increased risk for T1D, yet additional biomarkers are desperately in need to indicate this ?-cell destruction process and to help understanding the disease pathogenesis. Using liquid chromatography-mass spectrometry (LC-MS) based proteomics, we have identified a panel of novel serum proteins that are involved in the innate immune response, and can distinguish T1D from healthy controls with high sensitivity and specificity. In addition, most of these markers are not merely a result of hyperglycemia induced by type 2 diabetes. The long-term goal of this project is to provide thoroughly validated diagnostic and prognostic markers for T1D, and to gain additional insights into the pathogenesis of this disease. In the present application, we will extend our previous biomarker discovery effort to human pancreatic tissues obtained from T1D organ donors, and serial serum samples collected during the progression of T1D for a comprehensive identification of novel proteins and protein isoforms correlated to the progression of this disease. Findings from this new effort, along with our previous data, will be validated for disease early diagnosis and prognosis using longitudinally collected serum samples from the Diabetes Prevention Type 1 (DPT-1) cohort. Early diagnosis and risk assessment criteria will be established on the basis of the longitudinally changed peptide markers.